Signal transmission lines (‘transmission lines’) are ubiquitous in modern communications. These transmission lines transmit electromagnetic (EM) signals (‘signals’) from point to point, and take on various known forms including coaxial (“coax”) cables. For many years, coaxial cables included three primary elements, a center conductor, an outer conductor around the center conductor, and a dielectric between the center conductor and the outer conductor. However, a single eigenmode (‘single mode’) of signal propagation is desirable for coaxial cables insofar as multi-mode signal propagation is problematic because the desired propagation mode and higher-order modes can interfere with each other, and result in an uncontrolled and un-interpretable received signal. In high-bandwidth, high-quality signal environments multi-mode signal propagation is typically unacceptable.
Recently, a transmission line that fosters discrimination of a desired mode of signal propagation from the higher-order modes has been proposed. In the proposed transmission line, a resistive sheet is to be placed within the dielectric layer. However, requirements for characteristics and placement of the resistive sheet are specific, so the proposed transmission line cannot be obtained simply by placing any resistive sheet in any matter within a dielectric layer about, for example, the common axis of a coaxial cable.
The recent development of transmission lines with resistive sheets has encountered concerns in terms of fabrication, since traditional semi-rigid cable fabrication methods have a limited range of operation due to the cutoff frequency. For example, traditional semi-rigid cables are processed with a single dielectric layer and do not allow a hybrid multilayered construction. Significant capital expenses and manufacturing space are needed to manufacture semi-rigid cables due to large reel to reel minimum lot runs. Additionally, conventional semi-rigid cable processing and preparation methods can be crude insofar as known cut-off frequencies can tolerate such crude methods, whereas in a mode-less configuration these methods are not suitable. Moreover, conventional helically-wrapped flex cables do not utilize a centered resistive layer to increase frequency performance